Fusible link



C. P. HOWARD FUSIBLE LINK Jdne 14, 1932.

Filed Oct. 15, 1930 Patented June 14, 1932 UNITED STATES PATENT OFFICE CLIFTON P. HOWARD, OF WORCESTER, MASSACHUSETTS, ASSIGNOR TO ROCKWOOD SPRINKLER COMPANY OF MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS FUSIBLE LINK Application filed October 13, 1930. Serial No. 488,333.

This invention relates to a fusible link designed for use in temperature controlled apparatus such as sprinkler heads or fire doors.

It is the object of my invention to improve the construction of such links, to the end that the link may be more quickly responsive to a rapid rise in temperature and that it may yield more promptly and positively when heated above a predetermined minimum temperature.

A further object is to provide a construction which may be cheaply manufactured and which will be exceptionally reliable in use.

My invention further relates to arrangements and combinations of parts which will be hereinafter described and more particularly pointed out in the appended claims.

A preferred form of the invention is shown in the drawing, in which Fig. 1 is a side elevation of a sprinkler head having my invention embodied therein;

Fig. 2 is a side view of the fusible link, looking in the direction of the arrow 2 in Fig. 1;

Fig. 3 is a side elevation of one of the link plates;

Fig. 4- is a sectional view thereof, taken along the line 44 in Fig. 3;

Fig. 5 is a perspective view of a second link plate;

Fig. 6 is a perspective view of a locking plate; and

Fig. 7 is a sectional elevation, taken along the line 77 in Fig. 2.

Referring to Fig. 1, I have shown a sprinkler head of a commercial form comprising a threaded support 10 having an upwardly extending open frame structure 11. A cap 12 closes the passage through the threaded support 10 and is held firmly seated by locking levers or toggle members 18- which are pressed downward by an adjusting screw 14 threaded in theupper part of the open frame structure 11. The outer ends of the locking levers 13 are provided with notched ends or hook-like projecting portions 15, which are normally held from separation by my improved fusible link which will now be described.

My improved link in its simpler form comprises link plates 20 and 21 and av locking plate 22. The plates 20 and 21 are provided with openings 23 in their outer end portions to receive the hook-like projections 15 of the tangular opening 26, and the locking plate 22 is provided with a transversely extending end portion or offset lug 30. Preferably also the upper or body portion 32 of the locking plate 22, as viewed in F ig. 6, is of substantially thinner metal than the offset lug or projection 30.

The ends of the links and 21 are recessed, as indicated at 33, to clear the hook-like projections 15 when the link is in use, and the locking plate 22 is similarly recessed at 3-1 and for a similar purpose.

The plates 20 and 21 are assembled face to face, with the opening 26 in alignment with the offset portion 24 and shoulder 25. The

locking plate 22 is then assembled face to face With the link plate 21, with the projection extending through the opening 26 and into position for engagement with the shoulder 25. The displaced portion 24 forms a cover concealing the end of the projection 30 and assisting to protect the assembled parts from corrosion.

After the parts are thus assembled, the three plates are firmly secured together by a suitably selected fusible solder, which solder is sweated between the plates and is also flowed around the edges thereof, as indicated in Fig. 2.

When a link thus constructed is placed under tension, as by the tightening of the a;

screw 14 in a sprinkler head, the endwise tension on the plates 20 and 21 is taken by the interposed lug or projection 80, as clearly indicated in Fig. 7, and endwise separation of the parts cannot take place until the solder has melted sufficiently so that the plates 20 and 21 may separate or the locking plate 22 may swing to the dotted line position shown in Fig. 7.

It will be noted that the locking plate 22 is not secured in any Way to the link late 20 and that the link plate 21 and loc in plate 22 may separate bodily from the lin plate 20 without entire separation of the plates 21 and 22.

A li-n-k constructed as above described has been found by experiment to be extremely reliable and has also been found to respond very quickly to a sudden rise in temperature.

In my improved link, the provision of athinner body portion for the locking plate or plates increases the quickness of the release for sudden rise in temperature.

Having thus described my invention and the advantages thereof, I do not wish to" be limited to the details herein disclosed, other- Wise than asset forth inthe claim, but what I claim is A fusible link comprising first and second link plates and a locking plate, said l ink plates being assembled face to face in end- Wise reversed position, said first link plate having an opening and said second link plate having a portion partially severed-and displaced outwardly to provide a shoulder positioned adjacent said opening When the link plates are assembled and a cover adjacent said shoulder, and said locking plate being assembled face to face Withsaid first link plate and having a transversely disposed projection extending through the opening in said first link plate and engaging, the

I shoulder of said second link plate with the end of said projection covered and protected by said displaced portion, all of said plates being secured in the defined position by fusible solder melting at a predetermined temperature.

In testimony whereof I have hereunt afixed my signature.

CLIFTON P. HOWARD. 

